Taiwanese investigators probing the wreckage of the Kaoping motorway bridge that collapsed into a swollen river on 27 August are looking for signs that earlier scour prevention work caused the disaster.
More than 20 people were injured when two spans of the four lane crossing of the Kaoping river in south west Taiwan sagged, apparently because one of the multi-span structure's many support piers was undermined by scour. The bridge carried national highway 24 between the cities of Kaohsiung and Pingtung, and was used by more than 60,000 vehicles a day.
Local sources claimed that scour had been a major problem for the bridge for many years, exacerbated by unchecked illegal sand and gravel extraction close to the pier foundations.
Since 1990 there have been at least 12 attempts to protect and strengthen the foundations.
The last work was completed in January, and speculation that this diverted the river's flow against the unprotected foundations of Pier 22 soon surfaced in Taiwan.
A spokesman for the transport ministry said early estimates were that repair work would take at least eight months to complete. A preliminary report on the collapse was due to be presented to the government by the end of this week.